1. Lacking brilliance or vitality
   "a dull lacklustre life"
   - lackluster [US], lusterless [N. Amer], lustreless [Brit, Cdn] 
2. Lacking lustre or shine
   "staring with lacklustre eyes"
   - lackluster [US], lusterless [N. Amer], lustreless [Brit, Cdn]

See also: dull, hebetudinous

• unendingly
• unendowed
• unendurable
• unendurably
• unenergetic
• unenergetically
• unenforceable
• unenforced
• unengaged
• unenlightened
• unenlightening
• unenlightenment
• unenlivened
• unenterprising
• unenthusiastic
• unenthusiastically
• unentitled
• unenviable
• unequable
• unequal
• unequal to
• unequaled
• unequalised
• unequalized
• unequalled